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WO2018128113A1 - Matériau de noyau magnétique pour développateur électrographique, support de développateur électrographique et développateur - Google Patents

Matériau de noyau magnétique pour développateur électrographique, support de développateur électrographique et développateur Download PDF

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Publication number
WO2018128113A1
WO2018128113A1 PCT/JP2017/046426 JP2017046426W WO2018128113A1 WO 2018128113 A1 WO2018128113 A1 WO 2018128113A1 JP 2017046426 W JP2017046426 W JP 2017046426W WO 2018128113 A1 WO2018128113 A1 WO 2018128113A1
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Prior art keywords
carrier
core material
magnetic core
developer
ppm
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PCT/JP2017/046426
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English (en)
Japanese (ja)
Inventor
裕樹 澤本
哲也 植村
Original Assignee
パウダーテック株式会社
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Application filed by パウダーテック株式会社 filed Critical パウダーテック株式会社
Priority to CN201780080701.2A priority Critical patent/CN110114729B/zh
Priority to US16/474,508 priority patent/US10754271B2/en
Priority to EP17890275.5A priority patent/EP3567431A4/fr
Publication of WO2018128113A1 publication Critical patent/WO2018128113A1/fr

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
    • G03G9/1075—Structural characteristics of the carrier particles, e.g. shape or crystallographic structure
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/107—Developers with toner particles characterised by carrier particles having magnetic components
    • G03G9/108—Ferrite carrier, e.g. magnetite
    • G03G9/1085—Ferrite carrier, e.g. magnetite with non-ferrous metal oxide, e.g. MgO-Fe2O3
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/10—Developers with toner particles characterised by carrier particles
    • G03G9/113—Developers with toner particles characterised by carrier particles having coatings applied thereto
    • G03G9/1131—Coating methods; Structure of coatings

Definitions

  • the present invention relates to a magnetic core material for an electrophotographic developer, a carrier for an electrophotographic developer, and a developer.
  • the electrophotographic development method is a method in which toner particles in a developer are attached to an electrostatic latent image formed on a photoreceptor and developed, and the developer used in this method is composed of toner particles and carrier particles.
  • the cascade method has been used in the past, but at present, the magnetic brush method using a magnet roll is the mainstream. It is.
  • the carrier particles are agitated together with the toner particles in the developing box filled with the developer, thereby imparting a desired charge to the toner particles and thus being charged.
  • the carrier particles remaining on the developing roll holding the magnet are returned to the developing box from the developing roll, mixed and stirred with new toner particles, and used repeatedly for a certain period.
  • the two-component developer has the function of mixing and stirring the carrier particles with the toner particles, charging the toner particles, and further transporting them to the surface of the photoreceptor. Good controllability when designing. Therefore, the two-component developer is suitable for use in a full-color developing device that requires high image quality, a device that performs high-speed printing that requires reliability and durability of image maintenance, and the like.
  • image characteristics such as image density, fog, vitiligo, gradation, and resolving power show predetermined values from the initial stage, and these characteristics are in the printing life period. It needs to remain stable without fluctuating (ie, over a long period of use).
  • the characteristics of the carrier particles contained in the two-component developer are stable.
  • various carriers such as an iron powder carrier, a ferrite carrier, a resin-coated ferrite carrier, and a magnetic powder-dispersed resin carrier have been used as carrier particles forming the two-component developer.
  • Patent Document 1 Japanese Patent Laid-Open No. Hei 8-22150 discloses an electrophotography characterized in that a part of MnO, MgO, and Fe 2 O 3 is replaced with SrO.
  • a ferrite carrier for developer has been proposed, and according to the ferrite carrier, by reducing the variation in magnetization between ferrite carrier particles, it has excellent image quality and durability, is environmentally friendly, has a long life, and is excellent in environmental stability. It is said that there is.
  • Patent Document 2 Japanese Patent Laid-Open No. 2006-178278 proposes a ferrite carrier for an electrophotographic developer characterized by containing 40 to 500 ppm of zirconium. According to the ferrite carrier, a dielectric breakdown voltage is proposed. Therefore, the occurrence of charge leakage can be suppressed, and as a result, high image quality can be obtained.
  • Patent Document 3 Japanese Patent Application Laid-Open No. 2011-180296 discloses a ferrite core material in which a part of MnO and / or MgO is substituted with SrO, and is measured by an elution method of the ferrite core material. There has been proposed a carrier core material for an electrophotographic developer characterized by a Cl concentration of 0.1 to 100 ppm.
  • Patent Document 4 Japanese Patent Laid-Open No. 2016-252878 discloses that a ferrite magnetic material whose main components are additive elements such as Fe and Mn has an average particle diameter of 1 to 100 ⁇ m. And the total amount of impurities excluding additive elements and oxygen is 0.5% by mass or less, and the impurities are Si, Al, Cr, Cu, P, Cl, Ni, Mo, Zn, Ti, sulfur, Ca , Mn, and Sr have been proposed.
  • a magnetic carrier using a ferrite magnetic material in which the influence of impurities in the raw material is suppressed as a magnetic carrier core material for an electrophotographic developer is said to have a high magnetic force and an effect of suppressing carrier scattering.
  • the characteristics required for the carrier such as magnetization, electrical resistance and charging characteristics have been improved.
  • electrical resistance is an important factor that affects image characteristics such as carrier scattering, white spots, image density, fogging, and toner scattering, and the physical properties of the carrier core also affect the characteristics of the carrier.
  • the electric resistance of the carrier core material is controlled within a preferable range.
  • the carrier with inferior strength is cracked when agitated with the toner and the broken carrier adheres to the photoreceptor and causes image defects, it is also important that the strength of the carrier core itself is excellent. It is.
  • the present inventors have demonstrated that, in a magnetic core material for an electrophotographic developer, the content of a specific anion component measured by a combustion ion chromatography method and the BET specific surface area have excellent electric resistance characteristics and strength.
  • the knowledge that it is important in obtaining was obtained. Specifically, by appropriately controlling the content of a specific anion component and the BET specific surface area, the change in electrical resistance due to environmental fluctuations is reduced and the strength and charge imparting ability are excellent. As a result, the carrier And the knowledge that a good image can be stably obtained when used as a developer.
  • the amount of fluorine ions measured by combustion ion chromatography is a (ppm), the amount of chlorine ions is b (ppm), the amount of bromine ions is c (ppm), and the amount of nitrite ions is
  • d ppm
  • nitrate ion content is e (ppm)
  • sulfate ion content is f (ppm)
  • the value of the formula (1): a + b ⁇ 10 + c + d + e + f is 300 to 1300, and the BET specific surface area is 0.
  • a magnetic core material for an electrophotographic developer having a size of 06 to 0.25 m 2 / g is provided.
  • an electrophotographic developer carrier comprising the magnetic core material for an electrophotographic developer and a coating layer made of a resin provided on the surface of the magnetic core material. Is done.
  • a developer containing the carrier and a toner.
  • a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
  • the magnetic core material for an electrophotographic developer is a particle that can be used as a carrier core material, and a resin is coated on the carrier core material to form a magnetic carrier for electrophotographic development. By including the magnetic carrier for electrophotographic developer and toner, an electrophotographic developer is obtained.
  • Magnetic core material for electrophotographic developer The magnetic core material for an electrophotographic developer of the present invention (hereinafter sometimes referred to as a magnetic core material or a carrier core material) is a specific material measured by a combustion ion chromatography method. It has the characteristic that content of an anion component is controlled in the specific range.
  • the amount of fluorine ions in the magnetic core material is a (ppm)
  • the amount of chlorine ions is b (ppm)
  • the amount of bromine ions is c (ppm)
  • the amount of nitrite ions is d (ppm)
  • the amount of nitrate ions is 300 to 1300.
  • a carrier having excellent electric resistance characteristics and strength can be obtained.
  • the value of the formula (1) exceeds 1300, the environmental dependency of the electrical resistance increases.
  • anion component a specific anion component (hereinafter sometimes simply referred to as anion component), the greater the electrical resistance of the magnetic core material changes when the environment changes.
  • anion component easily absorbs moisture in the environment, the moisture content of the magnetic core material is increased and the ionic conductivity is increased particularly under high temperature and high humidity. As a result, the core material resistance is decreased. it is conceivable that.
  • the value of the formula (1) is less than 300, the fluctuation of the compression fracture strength becomes large, and the durability of the carrier is deteriorated.
  • a raw material having a high quality (low content of anion component) is used or a process for improving the quality is required.
  • productivity is inferior.
  • the value of the formula (1) is preferably 400 to 1200, particularly preferably 500 to 1100.
  • the content of the anionic component in the magnetic core material is preferably 300 to 1300 ppm, more preferably 400 to 1200 ppm, and still more preferably 500 to 1100 ppm in the formula (2): b ⁇ 10 + f.
  • content (ppm) of an anion component is a weight reference
  • the combustion ion chromatography method a sample is burned in an oxygen-containing gas stream, and the generated gas is absorbed in the absorption liquid. Thereafter, the halogen and sulfate ions absorbed in the absorption liquid are quantitatively analyzed by the ion chromatography method.
  • the content of the anion component is a value measured by a combustion ion chromatography method.
  • the detection of the anion component does not necessarily mean that it is contained in the magnetic core material in the form of the anion. It doesn't mean.
  • the magnetic core material is not limited to those containing a sulfur component in the form of sulfate ions, simple sulfur, metal sulfide, sulfate ions, or other These may be included in the form of sulfides.
  • the content value of the anion component described in this specification is a value measured by the combustion ion chromatography method under the conditions described in Examples described later.
  • the magnetic core material of the present invention has a BET specific surface area of 0.06 to 0.25 m 2 / g.
  • BET specific surface area is preferably 0.08 ⁇ 0.22m 2 / g, more preferably 0.10 ⁇ 0.20m 2 / g.
  • the BET specific surface area value described in the present specification is a value measured using a BET specific surface area measuring device under the conditions described in Examples described later.
  • the BET specific surface area of the magnetic core material can be set to the above range by adjusting the volume average particle diameter when the pre-fired product is pulverized and the firing temperature during the main firing. For example, the BET specific surface area is increased by reducing the volume average particle size of the calcined product, and the BET specific surface area is decreased by increasing the volume average particle size. Further, the BET specific surface area tends to be lowered by increasing the temperature during the main baking, and the BET specific surface area tends to be increased by decreasing the temperature during the main baking.
  • the main firing temperature is preferably 1130 ° C. to 1280 ° C., more preferably 1150 ° C. to 1250 ° C.
  • the composition of the magnetic core material is not particularly limited as long as it functions as a carrier core material, and a conventionally known composition can be used.
  • the magnetic core typically has a ferrite composition (ferrite particles), and preferably has a ferrite composition containing Fe, Mn, Mg, and Sr.
  • ferrite particles ferrite particles
  • the magnetic core material is particularly preferably one having a composition represented by the formula: (MnO) x (MgO) y (Fe 2 O 3 ) z and in which a part of MnO and MgO is substituted with SrO.
  • x 35 to 45 mol%
  • y 5 to 15 mol%
  • z 40 to 60 mol%
  • x + y + z 100 mol%.
  • This magnetic core material contains SrO in the composition. By containing SrO, the generation of low magnetization particles is suppressed.
  • SrO is a magnetoplumbite type ferrite in the form of Fe 2 O 3 and (SrO) ⁇ 6 (Fe 2 O 3 ) or Sr a Fe b O c (where a ⁇ 2, a + b ⁇ c ⁇ a + 1).
  • .5b) is a cubic strontium ferrite precursor (hereinafter referred to as Sr—Fe compound) having a perovskite type crystal structure, and spinel (MnO) x (MgO) y (Fe 2 A composite oxide that is solid-solved in O 3 ) z is formed.
  • This composite oxide of iron and strontium has the effect of increasing the charge imparting ability of the magnetic core material in combination with magnesium ferrite, which is a component containing MgO.
  • the Sr—Fe compound has a crystal structure similar to that of SrTiO 3 , which has a high dielectric constant, and contributes to higher charging of the magnetic core material.
  • Substitution of SrO is, (MnO) relative to x (MgO) y (Fe 2 O 3) z total amount, preferably from 0.1 to 2.5 mol%, more preferably 0.1 to 2.0 mol% More preferably, it is 0.3 to 1.5 mol%.
  • the volume average particle diameter (D 50 ) of the magnetic core material is preferably 20 to 50 ⁇ m.
  • the volume average particle diameter is more preferably 25 to 45 ⁇ m, still more preferably 30 to 40 ⁇ m.
  • the apparent density (AD) of the magnetic core is preferably 1.5 to 2.5 g / cm 3 .
  • the apparent density is more preferably 1.7 to 2.4 g / cm 3 , and still more preferably 2.0 to 2.3 g / cm 3 .
  • the pore volume of the magnetic core material is preferably 25 mm 3 / g or less. By setting the pore volume to 25 mm 3 / g or less, moisture adsorption in the atmosphere is suppressed, the change in the charge amount due to environmental fluctuations is reduced, and the resin is impregnated inside the core during resin coating. Therefore, it is not necessary to use a large amount of resin.
  • the pore volume is more preferably 0.1 to 20 mm 3 / g, still more preferably 1 to 20 mm 3 / g.
  • the pore volume value described in the present specification is a value measured and calculated under the conditions described in Examples described later using a mercury porosimeter.
  • the magnetic core material has a logarithmic value (LogR N / N ) of electrical resistance R N / N (unit: ⁇ ) in a normal temperature / normal humidity (N / N) environment, preferably 6.0 to 10.0. More preferably, it is 6.5 to 9.5, and even more preferably 7.0 to 9.0.
  • LogR N / N is an environment having a room temperature of 20 to 25 ° C. and a relative humidity of 50 to 60%
  • the logarithmic value is a value of a common logarithm.
  • the magnetic core material has an electrical resistance environment variation ratio (A / B) of preferably 1.5 or less, more preferably 1.4 or less.
  • the electrical resistance environment fluctuation ratio (A / B) is an index representing a change in electrical resistance due to an environmental difference, and as shown in the following formula, the electrical resistance in a low temperature / low humidity (L / L) environment.
  • the electrical resistance environment fluctuation ratio (A / B) By setting the electrical resistance environment fluctuation ratio (A / B) to 1.5 or less, it is possible to reduce the environmental dependency of the core material resistance, and to sufficiently suppress image defects caused by changes in the use environment. can do.
  • the H / H environment is an environment with a temperature of 30 to 35 ° C. and a relative humidity of 80 to 85%
  • the L / L environment is an environment with a temperature of 10 to 15 ° C. and a relative humidity of 10 to 15%. is there.
  • the lower limit of the electrical resistance environment fluctuation ratio (A / B) is not particularly limited, but is typically 1.1 or more.
  • the magnetic core material has an average compressive fracture strength (average compressive fracture strength) of preferably 200 mN or more, more preferably 230 mN or more, and even more preferably 260 mN or more.
  • the average of the compressive fracture strength is the average of the compressive fracture strength of individual particles in the particle aggregate of the magnetic core material.
  • the magnetic core material has a coefficient of variation in compressive fracture strength (compressive fracture strength variation coefficient) of preferably 40% or less, more preferably 37% or less, and still more preferably 34% or less.
  • the coefficient of variation in compressive fracture strength serves as an index of variation in the compressive fracture strength of individual particles in the magnetic core particle aggregate, and can be obtained by a method described later.
  • the lower limit of the compression fracture strength variation coefficient is not particularly limited, but is typically 5% or more.
  • the average compressive fracture strength (CS ave ) and the compressive fracture strength variation coefficient (CS var ) of the magnetic core material can be measured, for example, as follows. That is, an ultra-fine indentation hardness tester (ENT-1100a manufactured by Elionix Co., Ltd.) is used for measurement of compressive fracture strength. A sample dispersed on a glass plate is set on a tester and measured in an environment of 25 ° C. A flat indenter with a diameter of 50 ⁇ m ⁇ is used for the test, and a load of 49 mN / s is applied to 490 mN.
  • ENT-1100a manufactured by Elionix Co., Ltd. is used for measurement of compressive fracture strength.
  • a sample dispersed on a glass plate is set on a tester and measured in an environment of 25 ° C.
  • a flat indenter with a diameter of 50 ⁇ m ⁇ is used for the test, and a load of 49 mN / s is applied to 490 mN.
  • a particle to be used for measurement there is only one particle on the measurement screen (width 130 ⁇ m ⁇ length 100 ⁇ m) of the ultra micro indentation hardness tester, it has a spherical shape, and the major axis measured by the software attached to ENT-1100a The average value of the minor axis is selected so that the volume average particle diameter is ⁇ 2 ⁇ m.
  • the compressive fracture strength of 100 particles is measured, and the average compressive fracture strength (CS ave ) is determined by adopting 80 compressive fracture strengths obtained by subtracting 10 from the maximum value and the minimum value as data.
  • the compression fracture strength coefficient of variation (CS var ) is obtained from the following equation by calculating the standard deviation (CS sd ) for the 80 pieces.
  • the magnetic core material (carrier core material) for an electrophotographic developer of the present invention has an object of improving charging characteristics, resistance characteristics, and durability, and is an anion component measured by a combustion ion chromatography method. Content and BET specific surface area are controlled. As a result, the change in electrical resistance due to environmental fluctuations is small, and the strength and strength deviation are suppressed and the charge imparting ability is excellent. As a result, a carrier capable of obtaining a good image without defects can be obtained. As far as the present inventors know, there is no known technique for controlling the content of the anionic component and the BET specific surface area.
  • Patent Document 3 defines the Cl concentration measured by the elution method with the object of obtaining a high charge amount and suppressing environmental fluctuation of the charge amount, but the influence of anion components other than Cl.
  • the elution method is a method for measuring the concentration of components present on the particle surface, and the measurement principle is completely different from the ion chromatography method.
  • Patent Document 4 has an object of suppressing carrier scattering, and by defining the total amount of impurities in the ferrite magnetic material, it has excellent magnetic characteristics and suppresses carrier scattering. This document 4 simply focuses on reducing the total amount of impurities such as Si and Al as much as possible, and does not teach controlling the content of the anion component within a specific range. There is no disclosure about the BET specific surface area. Thus, the present invention and Patent Documents 3 and 4 differ not only in the problem but also in the operational effect.
  • Carrier for electrophotographic developer of the present invention (sometimes simply referred to as a carrier) is preferably the surface of the magnetic core material (carrier core material) coated with a coating resin.
  • Carrier properties may be affected by the materials and properties present on the carrier surface. Therefore, by coating the surface with an appropriate resin, desired carrier characteristics can be imparted with high accuracy.
  • Coating resin is not particularly limited.
  • silicone resins modified with resins such as acrylic resin, polyester resin, epoxy resin, polyamide resin, polyamideimide resin, alkyd resin, urethane resin, and fluororesin can be used.
  • a thermosetting resin is preferably used.
  • thermosetting resins include epoxy resins, phenol resins, silicone resins, unsaturated polyester resins, urea resins, melamine resins, alkyd resins, and resins containing them.
  • the resin coating amount is preferably 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the magnetic core material (before resin coating).
  • the coating resin can contain a charge control agent.
  • the charge control agent include various charge control agents generally used for toners and various silane coupling agents.
  • the types of charge control agents and coupling agents that can be used are not particularly limited, but charge control agents such as nigrosine dyes, quaternary ammonium salts, organometallic complexes, and metal-containing monoazo dyes, aminosilane coupling agents, and fluorine-based silane couplings. An agent or the like is preferable.
  • amine-based compounds are examples of materials having a strong positive polarity.
  • An amine compound is an effective material because it has a strong positive polarity and can sufficiently make the toner negative.
  • various compounds can be used. Examples include aminosilane coupling agents, amino-modified silicone oils, quaternary ammonium salts, and the like. Among such amine compounds, aminosilane coupling agents are particularly suitable.
  • any of a compound containing a primary amine, a secondary amine, or both can be used.
  • Examples include N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, N -Aminopropyltrimethoxysilane, N-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyl trimethoxysilane It is done.
  • the amine compound When the amine compound is used by mixing with a resin, it is desirable to contain 2 to 50% by weight in the solid content of the coating resin. If the content of the amine compound is less than 2% by weight, there is no content effect, and if it exceeds 50% by weight, no further content effect is obtained, which is economically disadvantageous. Moreover, when there are too many amine compounds, a malfunction may arise in compatibility with coating resin, etc., and it becomes easy to become a non-uniform resin mixture, which is not preferable.
  • the base resin may be modified in advance.
  • examples thereof include amino-modified silicone resins, amino group-containing acrylic resins, amino group-containing epoxy resins, and the like. These resins may be used alone or in combination with other resins.
  • the amount of the amino group present in the entire resin is appropriately determined from its chargeability, compatibility and the like.
  • a conductive agent can be added to the coating resin for the purpose of controlling carrier characteristics.
  • the addition amount is 0.25 to 20.0% by weight, preferably 0.5 to 15.0% by weight, particularly preferably 1.0 to 10.0% by weight, based on the solid content of the coating resin.
  • the conductive agent include conductive carbon, oxides such as tin oxide and titanium oxide, and various organic conductive agents.
  • the carrier has a logarithmic value (LogR N / N ) of electrical resistance R N / N (unit: ⁇ ) in a normal temperature / normal humidity (N / N) environment, preferably 7.0 to 13.0. It is preferably 7.5 to 12.5, and more preferably 8.0 to 12.0.
  • LogR N / N logarithmic value of electrical resistance R N / N (unit: ⁇ ) in a normal temperature / normal humidity (N / N) environment, preferably 7.0 to 13.0. It is preferably 7.5 to 12.5, and more preferably 8.0 to 12.0.
  • the carrier has an electrical resistance environment variation ratio (C / D) of preferably 1.5 or less, more preferably 1.4 or less.
  • the electrical resistance environment fluctuation ratio (C / D) is a logarithmic value (LogR L / L ) of the electrical resistance R L / L (unit: ⁇ ) in a low temperature / low humidity (L / L) environment as shown in the following formula. ) Of the electrical resistance R H / H (unit: ⁇ ) in a high temperature / high humidity (H / H) environment to a logarithmic value (Log R H / H ).
  • the lower limit of the electrical resistance environment fluctuation ratio (C / D) is not particularly limited, but is typically 1.1 or more.
  • the charge amount of the carrier is preferably 20 to 80 ⁇ C / g, more preferably 30 to 70 ⁇ C / g, still more preferably 40 to 60 ⁇ C / g.
  • a magnetic core material for electrophotographic developer is first prepared. In order to produce a magnetic core material, an appropriate amount of raw materials are weighed, and then pulverized and mixed in a ball mill or vibration mill for 0.5 hour or more, preferably 1 to 20 hours.
  • the raw material is not particularly limited, but is preferably selected so as to have a composition containing the above-described elements.
  • the pulverized material thus obtained is pelletized using a pressure molding machine or the like, and then calcined at a temperature of 700 to 1300 ° C. Without using a pressure molding machine, it may be pulverized and then added with water to form a slurry, and granulated using a spray dryer. After calcination, the mixture is further pulverized with a ball mill or a vibration mill, and then water and, if necessary, a dispersant, a binder and the like are added. After adjusting the viscosity, the mixture is granulated with a spray dryer and granulated. When pulverizing after calcination, water may be added and pulverized with a wet ball mill, a wet vibration mill or the like.
  • the pulverizer such as the above-mentioned ball mill and vibration mill is not particularly limited, but in order to disperse the raw materials effectively and uniformly, it is preferable to use fine beads having a particle diameter of 1 mm or less for the medium to be used. Further, the degree of pulverization can be controlled by adjusting the particle size, composition, and pulverization time of the beads used.
  • the obtained granulated product is held at a temperature of 800 to 1500 ° C. for 1 to 24 hours in an atmosphere in which the oxygen concentration is controlled to perform main firing.
  • a rotary electric furnace, a batch electric furnace or a continuous electric furnace is used, and an atmosphere at the time of firing is oxygenated by implanting an inert gas such as nitrogen or a reducing gas such as hydrogen or carbon monoxide.
  • the concentration may be controlled.
  • the fired product obtained in this way is crushed and classified.
  • the particle size is adjusted to a desired particle size using an existing air classification, mesh filtration method, sedimentation method, or the like.
  • the surface can be heated at a low temperature to perform an oxide film treatment, and the electric resistance can be adjusted.
  • the oxide film treatment can be performed by heat treatment at, for example, 300 to 700 ° C. using a general rotary electric furnace, batch electric furnace or the like.
  • the thickness of the oxide film formed by this treatment is preferably 0.1 nm to 5 ⁇ m. When the thickness is 0.1 nm or more, the effect of the oxide film layer can be made sufficient, and when the thickness is 5 ⁇ m or less, a decrease in magnetization and an excessive increase in resistance are suppressed. Moreover, you may reduce
  • a carrier by coating the surface of the magnetic core with a resin after producing the magnetic core.
  • the coating resin used here is as described above.
  • the carrier characteristics are often influenced by materials and properties existing on the carrier surface. Therefore, the desired carrier characteristics can be accurately adjusted by coating the surface with an appropriate resin.
  • a coating method it can be coated by a known method such as a brush coating method, a dry method, a spray drying method using a fluidized bed, a rotary drying method, an immersion drying method using a universal stirrer, or the like. In order to improve the coverage, a fluidized bed method is preferred.
  • an external heating system or an internal heating system may be used.
  • a fixed or fluid electric furnace, a rotary electric furnace, or a burner furnace can be used.
  • microwave baking may be used.
  • a UV curable resin is used as the coating resin, a UV heater is used.
  • the baking temperature varies depending on the resin to be used, a temperature equal to or higher than the melting point or the glass transition point is necessary.
  • a thermosetting resin or a condensation-crosslinking resin it is necessary to raise the temperature to a point where the curing proceeds sufficiently.
  • the developer of the present invention comprises the carrier for an electrophotographic developer and a toner.
  • Particulate toner (toner particles) constituting the developer includes pulverized toner particles produced by a pulverization method and polymerized toner particles produced by a polymerization method.
  • the toner particles used in the present invention may be toner particles obtained by any method.
  • the pulverized toner particles are, for example, a binder resin, a charge control agent, and a colorant are sufficiently mixed with a mixer such as a Henschel mixer, then melt-kneaded with a twin screw extruder or the like, cooled, pulverized, classified, It can be obtained by adding an external additive such as silica powder and titania and then mixing with a mixer or the like.
  • a mixer such as a Henschel mixer
  • the binder resin constituting the pulverized toner particles is not particularly limited, but polystyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, Furthermore, rosin-modified maleic acid resin, epoxy resin, polyester resin, polyurethane resin and the like can be mentioned. These may be used alone or in combination.
  • Any charge control agent can be used.
  • nigrosine dyes and quaternary ammonium salts can be used for positively charged toners
  • metal-containing monoazo dyes can be used for negatively charged toners.
  • colorant conventionally known dyes and pigments can be used.
  • carbon black, phthalocyanine blue, permanent red, chrome yellow, phthalocyanine green, etc. can be used.
  • external additives such as silica powder and titania for improving the fluidity and aggregation resistance of the toner can be added according to the toner particles.
  • Polymerized toner particles are toner particles produced by a known method such as a suspension polymerization method, an emulsion polymerization method, an emulsion aggregation method, an ester extension polymerization method, or a phase inversion emulsification method.
  • Such polymerized toner particles are prepared by, for example, mixing and stirring a colored dispersion obtained by dispersing a colorant in water using a surfactant, a polymerizable monomer, a surfactant and a polymerization initiator in an aqueous medium.
  • the polymerizable monomer is emulsified and dispersed in an aqueous medium, polymerized while stirring and mixing, and then a salting-out agent is added to salt out the polymer particles.
  • Polymerized toner particles can be obtained by filtering, washing and drying the particles obtained by salting out. Thereafter, external additives such as silica powder and titania are added to the dried toner particles as necessary.
  • a fixability improving agent and a charge control agent can be blended and obtained.
  • Various characteristics of the polymerized toner particles can be controlled and improved.
  • a chain transfer agent can be used to improve the dispersibility of the polymerizable monomer in the aqueous medium and adjust the molecular weight of the resulting polymer.
  • the polymerizable monomer used for the production of the polymerized toner particles is not particularly limited.
  • styrene and its derivatives ethylene unsaturated monoolefins such as ethylene and propylene, vinyl halides such as vinyl chloride, Vinyl esters such as vinyl acetate, ⁇ -methylene aliphatic monocarboxylic acids such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, dimethylamino acrylate and diethylaminoester methacrylate Examples include esters.
  • colorant used in the preparation of the polymerized toner particles
  • conventionally known dyes and pigments can be used.
  • carbon black, phthalocyanine blue, permanent red, chrome yellow, phthalocyanine green, and the like can be used.
  • the surface of these colorants may be modified using a silane coupling agent, a titanium coupling agent, or the like.
  • an anionic surfactant As the surfactant used in the production of the polymerized toner particles, an anionic surfactant, a cationic surfactant, an amphoteric surfactant and a nonionic surfactant can be used.
  • examples of the anionic surfactant include fatty acid salts such as sodium oleate and castor oil, alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate, alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate, and alkyl naphthalene sulfonic acids. Salt, alkyl phosphate ester salt, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl sulfate ester salt and the like.
  • nonionic surfactant examples include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin, fatty acid ester, and oxyethylene-oxypropylene block polymer.
  • examples of the cationic surfactant include alkylamine salts such as laurylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride and stearyltrimethylammonium chloride.
  • amphoteric surfactants include aminocarboxylates and alkylamino acids.
  • the surfactant as described above can be used in an amount usually in the range of 0.01 to 10% by weight with respect to the polymerizable monomer.
  • the amount of such a surfactant used affects the dispersion stability of the monomer and also affects the environmental dependency of the obtained polymerized toner particles. It is preferably used in an amount within the above range that is ensured and does not exert an excessive influence on the environment dependency of the polymerized toner particles.
  • the polymerization initiator includes a water-soluble polymerization initiator and an oil-soluble polymerization initiator, and any of them can be used in the present invention.
  • the water-soluble polymerization initiator that can be used in the present invention include persulfates such as potassium persulfate and ammonium persulfate, water-soluble peroxide compounds, and oil-soluble polymerization initiators.
  • examples thereof include azo compounds such as azobisisobutyronitrile and oil-soluble peroxide compounds.
  • examples of the chain transfer agent include mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, carbon tetrabromide, and the like.
  • the polymerized toner particles used in the present invention contain a fixability improving agent
  • a natural wax such as carnauba wax, an olefinic wax such as polypropylene or polyethylene can be used as the fixability improving agent.
  • the charge control agent to be used is not particularly limited, and nigrosine dyes, quaternary ammonium salts, organometallic complexes, metal-containing monoazo dyes, etc. Can be used.
  • Examples of the external additive used for improving the fluidity of polymerized toner particles include silica, titanium oxide, barium titanate, fluororesin fine particles, and acrylic resin fine particles. Can be used in combination.
  • examples of the salting-out agent used for separating the polymer particles from the aqueous medium include metal salts such as magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride, and sodium chloride.
  • the average particle diameter of the toner particles produced as described above is in the range of 2 to 15 ⁇ m, preferably 3 to 10 ⁇ m, and the polymer toner particles have higher particle uniformity than the pulverized toner particles.
  • the average particle size By setting the average particle size to 2 ⁇ m or more, the charging ability is improved and fog and toner scattering are further suppressed, and by setting the average particle size to 15 ⁇ m or less, the image quality is further improved.
  • the mixing ratio of the carrier and the toner is preferably set to 3 to 15% by weight.
  • a developer obtained by mixing the carrier and toner manufactured as described above can be used as a replenishment developer.
  • the mixing ratio of the carrier and the toner is 1 to 50 parts by weight of the toner with respect to 1 part by weight of the carrier.
  • the developer of the present invention prepared as described above is a two-component having toner and carrier while applying a bias electric field to an electrostatic latent image formed on a latent image holding member having an organic photoconductor layer.
  • the present invention can be used in digital copiers, printers, fax machines, printers, and the like that use a developing system in which reversal development is performed with a magnetic brush of developer. Further, the present invention can also be applied to a full color machine using an alternating electric field, which is a method of superimposing an AC bias on a DC bias when a developing bias is applied from the magnetic brush to the electrostatic latent image side.
  • Example 1 (1) Preparation of MnO magnetic core (carrier core material): 39.6 mol%, MgO: 9.6 mol%, Fe 2 O 3: 50 mol%, and SrO: material to be 0.8 mol%
  • carrier core material 39.6 mol%
  • MgO 9.6 mol%
  • Fe 2 O 3 50 mol%
  • SrO material to be 0.8 mol%
  • 34.2 kg of Fe 2 O 3 as the raw material 12.9 kg of trimanganese tetraoxide as the MnO raw material, 2.4 kg of magnesium hydroxide as the MgO raw material, and 0.5 kg of strontium carbonate as the SrO raw material, respectively It was.
  • the obtained slurry was squeezed and dehydrated with a belt press, water was added to the cake, and the mixture was again pulverized for 4 hours using a wet media mill (horizontal bead mill, 1 mm diameter zirconia beads) to obtain slurry 1.
  • the size of the particles of the slurry in 1 results measured at Microtrac, D 50 is about 2 [mu] m.
  • grains by which resin was hardened were pick_out
  • the volume average particle diameter (D 50 ) of the magnetic core material was measured using a Microtrac particle size analyzer (Model 9320-X100 manufactured by Nikkiso Co., Ltd.). Water was used as the dispersion medium. 10 g of sample and 80 ml of water were placed in a 100 ml beaker, and 2 to 3 drops of a dispersant (sodium hexametaphosphate) was added. Next, using an ultrasonic homogenizer (UH-150 type, manufactured by SMT Co. LTD.), The output level was set to 4 and dispersion was performed for 20 seconds. Thereafter, bubbles formed on the surface of the beaker were removed, and the sample was put into the apparatus for measurement.
  • a dispersant sodium hexametaphosphate
  • the apparent density (AD) of the magnetic core material was measured according to JIS-Z2504 (Apparent density test method of metal powder).
  • the BET specific surface area of the magnetic core material was measured using a BET specific surface area measuring apparatus (Macsorb HM model 1210 manufactured by Mountec Co., Ltd.). The measurement sample was put in a vacuum dryer, treated at 200 ° C. for 2 hours, held in the dryer until it became 80 ° C. or lower, and then taken out from the dryer. Thereafter, the sample was filled so that the cells were dense and set in the apparatus. Measurements were made after pretreatment at a degassing temperature of 200 ° C. for 60 minutes.
  • the content of the anion component in the magnetic core material was measured by a quantitative analysis under the following conditions by the combustion ion chromatography method.
  • -Combustion device AQF-2100H manufactured by Mitsubishi Chemical Analytech Co., Ltd.
  • -Sample amount 50mg -Combustion temperature: 1100 ° C
  • Combustion time 10 minutes-Ar flow rate: 400 ml / min -O 2 flow rate: 200 ml / min -Humidification
  • Air flow rate 100ml / min -Absorbent: 1% by weight of hydrogen peroxide in the eluent below
  • IC-2010 manufactured by Tosoh Corporation -Column: TSKgel SuperIC-Anion HS (4.6 mm ID ⁇ 1 cm + 4.6 mm ID ⁇ 10 cm) - Eluent: aqueous solution of pure water with respect NaHCO 3 3.8 mmol, and dissolved Na 2 CO 3 3.0 mmol of 1L - flow rate: 1.5 mL / min -Column temperature: 40 ° C -Injection volume: 30 ⁇ L -Measurement mode: Suppressor method-Detector: CM detector-Standard sample: Anion mixed standard solution manufactured by Kanto Chemical Co., Inc.
  • the content of the cation component in the magnetic core material was measured as follows. First, an acid solution was added to the ferrite particles and heated to completely dissolve the ferrite particles. Next, the dissolved solution was quantitatively analyzed using an ICP emission analyzer (ICPS-1000IV manufactured by Shimadzu Corporation), and the analysis result was converted into the content of ferrite particles.
  • an acid solution was added to the ferrite particles and heated to completely dissolve the ferrite particles.
  • the dissolved solution was quantitatively analyzed using an ICP emission analyzer (ICPS-1000IV manufactured by Shimadzu Corporation), and the analysis result was converted into the content of ferrite particles.
  • the electrical resistance characteristics of the magnetic core material and the carrier in a normal temperature and normal humidity (N / N) environment, a high temperature and high humidity (H / H) environment, and a low temperature and low humidity (L / L) environment are as follows. Asked.
  • the electrical resistance (R N / N ) of the magnetic core material in an N / N environment was measured as follows. That is, nonmagnetic parallel plate electrodes (10 mm ⁇ 40 mm) were opposed to each other with an electrode spacing of 2.0 mm, and 200 mg of a sample was weighed and filled between them.
  • a sample is held between the electrodes by attaching a magnet (surface magnetic flux density: 1500 Gauss, area of the magnet in contact with the electrode: 10 mm ⁇ 30 mm) to the parallel plate electrodes, a voltage of 100 V is applied, and an insulation resistance meter (Toa The electrical resistance R N / N (unit: ⁇ ) was measured using SM-8210 manufactured by Decka Corporation, and the logarithmic value (LogR N / N ) was determined.
  • the term “normal temperature and humidity” as used herein refers to an environment where the temperature is 20 to 25 ° C. and the humidity is 50 to 60%. In the measurement, the sample is placed in a constant temperature and humidity chamber controlled to the room temperature and humidity. After exposure for more than an hour.
  • the electrical resistance (R H / H ) of the magnetic core material in the H / H environment was measured as follows. That is, after exposing the sample to a room in which the room temperature and humidity are controlled so that the H / H environment has a temperature of 30 to 35 ° C. and a relative humidity of 80 to 85% for 12 hours or more, The electrical resistance R H / H (unit: ⁇ ) was measured by the same method as the resistance, and the logarithmic value (Log R H / H ) was determined. At this time, the distance between the electrodes was 2.0 mm, and the applied voltage was 100V.
  • the electrical resistance (R L / L ) of the magnetic core material under the L / L environment was measured as follows. That is, after exposing the sample to a room where the room temperature and humidity are controlled so that the L / L environment has a temperature of 10 to 15 ° C. and a relative humidity of 10 to 15% for 12 hours or more, The electric resistance R L / L (unit: ⁇ ) was measured by the same method as the resistance, and the logarithmic value (Log R L / L ) was obtained. At this time, the distance between the electrodes was 2.0 mm, and the applied voltage was 100V.
  • the electrical resistance ( RN / N , RH / H, and RL / L ) of the carrier under the N / N environment, H / H environment, and L / L environment is the same as in the case of the magnetic core material.
  • the carrier was measured and the electrical resistance environment fluctuation ratio (C / D) of the carrier was determined from the following equation.
  • CS ave compressive fracture strength
  • CS var compressive fracture strength variation coefficient
  • a particle to be used for measurement there is only one particle on the measurement screen (width 130 ⁇ m ⁇ length 100 ⁇ m) of the ultra micro indentation hardness tester, it has a spherical shape, and the major axis measured by the software attached to ENT-1100a The average value of the minor axis was selected so that the volume average particle diameter is ⁇ 2 ⁇ m.
  • the compressive fracture strength of 100 particles was measured, and 80 compressive fracture strengths obtained by subtracting 10 from the maximum value and the minimum value were adopted as data, and the average compressive fracture strength (CS ave ) was obtained.
  • the compression fracture strength variation coefficient (CS var ) was obtained from the following formula by calculating the standard deviation (CS sd ) for the 80 pieces.
  • the charge amount of the carrier was measured as follows. First, a carrier and a commercially available negative polarity toner (cyan toner, for DocuPrint C3530 manufactured by Fuji Xerox Co., Ltd.) used in a full color printer were weighed so that the toner concentration was 8.0% by weight and the total weight was 50 g. . The weighed carrier and toner were exposed to a normal temperature and humidity environment of 20 to 25 ° C. and a relative humidity of 50 to 60% for 12 hours or more. Thereafter, the sample and the toner were put in a 50 cc glass bottle and stirred for 15 minutes at a rotation speed of 120 rpm to obtain a developer.
  • cyan toner for DocuPrint C3530 manufactured by Fuji Xerox Co., Ltd.
  • a magnet having a total of 8 poles (flux density 0.1 T) is alternately placed on the inner side of a cylindrical aluminum tube (hereinafter referred to as a sleeve) having a diameter of 31 mm and a length of 76 mm.
  • a magnet roll in which the sleeve is disposed, and a cylindrical electrode having a sleeve and a 5.0 mm gap are disposed on the outer periphery of the sleeve.
  • a DC voltage of 2000 V is applied between the outer electrode and the sleeve while rotating the inner magnet roll at 100 rpm while fixing the outer aluminum tube.
  • Example 2 A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 1 except that the conditions during pulverization of the calcined product were changed.
  • (1-1) pre-calcined product pulverization in Example 1 was changed as follows. That is, using a dry media mill (vibration mill, 1/8 inch diameter stainless steel beads), after pulverizing for 6 hours until the average particle size becomes about 5 ⁇ m, water is added, and a wet media mill (horizontal type) It was pulverized for 4 hours using a bead mill, 1 mm diameter zirconia beads).
  • the obtained slurry was pressed and dehydrated with a screw press, water was added to the cake, and the mixture was again pulverized for 4 hours using a wet media mill (horizontal bead mill, 1 mm diameter zirconia beads) to obtain slurry 2.
  • a wet media mill horizontal bead mill, 1 mm diameter zirconia beads
  • Example 3 A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 1 except that the conditions during pulverization of the calcined product were changed.
  • (1-1) pre-calcined product pulverization in Example 1 was changed as follows. That is, using a dry media mill (vibration mill, 1/8 inch diameter stainless steel beads), after pulverizing for 6 hours until the average particle size becomes about 5 ⁇ m, water is added, and a wet media mill (horizontal type)
  • a slurry 3 was obtained by pulverizing for 6 hours using a bead mill and 1 mm diameter zirconia beads). The slurry being pulverized was concentrated by cross-flow filtration and added with water simultaneously with the pulverization.
  • the D 50 was about 2 ⁇ m.
  • Example 4 A magnetic core material and a carrier were produced and evaluated in the same manner as in Example 1 except that raw materials having different lots were used.
  • Example 5 A magnetic core material and a carrier were produced and evaluated in the same manner as in Example 2 except that raw materials in different lots were used.
  • Example 6 A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 3 except that raw materials having different lots were used.
  • Example 7 (comparative example) A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 1 except that the conditions during pulverization of the calcined product were changed.
  • (1-1) pre-calcined product pulverization in Example 1 was changed as follows. That is, using a dry media mill (vibration mill, 1/8 inch diameter stainless steel beads), after pulverizing for 6 hours until the average particle size becomes about 5 ⁇ m, water is added, and a wet media mill (horizontal type) A slurry 7 was obtained by grinding for 6 hours using a bead mill and 1 mm diameter zirconia beads). The particle size of the slurry 7 (volume average particle diameter of the pulverized product) results measured at Microtrac, D 50 is about 2 [mu] m.
  • Example 8 (comparative example) A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 7 except that raw materials having different lots were used.
  • Example 9 (comparative example) A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 1 except that the conditions during pulverization of the calcined product were changed.
  • (1-1) pre-calcined product pulverization in Example 1 was changed as follows. That is, using a dry media mill (vibration mill, 1/8 inch diameter stainless steel beads), after pulverizing for 6 hours until the average particle size becomes about 5 ⁇ m, water is added, and a wet media mill (horizontal type) It was pulverized for 3 hours using a bead mill, 1 mm diameter zirconia beads).
  • the obtained slurry was squeezed and dehydrated with a belt press, water was added to the cake, and the mixture was again pulverized for 2 hours using a wet media mill (horizontal bead mill, 1 mm diameter zirconia beads).
  • the obtained slurry was again squeezed and dehydrated with a belt press, water was added to the cake, and the mixture was again pulverized for 3 hours using a wet media mill (horizontal bead mill, 1 mm diameter zirconia beads) to obtain slurry 9. .
  • the D 50 was about 2 ⁇ m.
  • Example 10 (comparative example) A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 1 except that the conditions (firing temperature) for main firing were changed.
  • the conditions for the main firing were performed as follows. That is, a fired product was obtained by holding for 5 hours at a firing temperature of 1110 ° C. and an oxygen concentration of 0.6 vol% in a tunnel type electric furnace.
  • Example 11 (comparative example) A magnetic core material and a carrier were prepared and evaluated in the same manner as in Example 1 except that the conditions (firing temperature) for main firing were changed.
  • the conditions for the main firing were performed as follows. That is, in a tunnel-type electric furnace, a fired product was obtained by holding for 5 hours at a firing temperature of 1280 ° C. and an oxygen concentration of 0.6% by volume.
  • Example 1 to 11 the obtained evaluation results were as shown in Tables 1 and 2.
  • the electrical resistance environment variation ratio (A / B) was small, the compression fracture strength (CS ave ) was excellent, and the variation coefficient (CS var ) of the compression fracture strength was small.
  • the formula (1) is excessively large, and as a result, the electrical resistance environment fluctuation ratio (A / B) is inferior.
  • Example 9 which is a comparative example, the formula (1) is excessively small, and as a result, the coefficient of variation (CS var ) in compressive fracture strength is inferior.
  • Comparative Example 10 Since Comparative Example 10 has a large BET specific surface area, the average compressive fracture strength was low, and in Example 11, the carrier charge amount was low. From these results, according to the present invention, a magnetic core material for an electrophotographic developer and an electron having a small change in electrical resistance due to environmental fluctuations, an excellent strength and a charge imparting ability, and a good image without defects can be obtained. It can be seen that a carrier for a photographic developer and a developer containing the carrier can be provided.
  • a magnetic core material for an electrophotographic developer and an electron capable of stably obtaining a good image when it is used as a carrier because the change in electrical resistance due to environmental fluctuations is reduced and the strength and charging ability are excellent.
  • a carrier for a photographic developer and a developer containing the carrier can be provided.

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Abstract

L'invention concerne un matériau de noyau magnétique pour un développateur électrographique, ledit matériau présentant peu de changements de résistance électrique dus à des variations environnementales, ainsi qu'une excellente résistance et une excellente capacité de transmission de charge, et permettant également d'obtenir une bonne image sans défauts. L'invention concerne également un support pour un développateur électrographique et un développateur équipé dudit support. L'invention porte plus précisément sur un matériau de noyau magnétique pour un développateur électrographique, où la surface spécifique BET est de 0,06 à 0,25 m2/g, et la formule (1), c'est-à-dire, a+b×10+c+d+e+f, a une valeur comprise entre 300 et 1300 inclus, où, tels que mesurés par chromatographie d'ions de combustion, a (ppm) est la quantité d'ions fluor, b (ppm) est la quantité d'ions chlore, c (ppm) est la quantité d'ions bromure, d (ppm)) est la quantité d'ions nitrite, e (ppm) est la quantité d'ions nitrate, et f (ppm) est la quantité d'ions sulfate.
PCT/JP2017/046426 2017-01-04 2017-12-25 Matériau de noyau magnétique pour développateur électrographique, support de développateur électrographique et développateur WO2018128113A1 (fr)

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US16/474,508 US10754271B2 (en) 2017-01-04 2017-12-25 Magnetic core material for electrophotographic developer, carrier for electrophotographic developer, and developer
EP17890275.5A EP3567431A4 (fr) 2017-01-04 2017-12-25 Matériau de noyau magnétique pour développateur électrographique, support de développateur électrographique et développateur

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